At work we have a 500GB My Book Essentials hard drive that was giving fits and taking 4 days to format. So I ran WDC's diagnostics on it. The results we were getting were inconsistent, yet convinced me that there was a failure.
So I went to the WDC web site http://www.wdc.com/ and submitted a request to their online support. To which I get this automated email response with web links and things to try which are of little help.
So I reply to the email, like it says I can, and re-describe the problems and error codes I was seeing.
It took 8 days and three messages from me before I got the response from WDC to submit an RMA for its exchange.
The RMA was submitted on the 7th and the status of our Advance Exchange is "In Process for Shipment". It apparently takes another 3-5 business days to get the Advance Replacement drive sent out.